Diagnosis of hypoglycaemia: effects of blood sample handling and evaluation of a glucose photometer in the low glucose range

Hypoglycaemia is a dangerous condition. Rapid and reliable blood glucose measurements are necessary for the initiation of treatment to reduce the risk of neurological sequelae. The aim of this study was to compare a bedside glucose photometer (HemoCue) with three methods of handling blood glucose measurements in a routine chemistry laboratory and to estimate the reliability of glucose measurements in the low glucose range during controlled hypoglycaemia. Nine children underwent an arginine-insulin tolerance test as part of a growth hormone deficiency investigation. Only blood samples below 4.0mmoll^-1 were included ( n = 35). Significant (0.3-1.0mmoll^-1) differences in blood glucose measurements were found, depending on the handling of the blood sample. The differences seem primarily to be due to glycolysis which occurred in spite of the addition of the glycolysis inhibitor NaF to the blood samples. Immediate centrifugation and analysis of the supernatant or immediate analysis with the HemoCue results in higher, and presumably more correct, values than routine procedures and permits a more accurate diagnosis of hypoglycaemia.     

Evaluation of the validity of a rapid method for measuring high and low haemoglobin levels in whole blood donors

Background

Haemoglobin screening methods need to be highly sensitive to detect both low and high haemoglobin levels and avoid unnecessary rejection of potential blood donors. The aim of this study was to evaluate the accuracy of measurements by HemoCue in blood donors.

Materials and methods

Three hundred and fourteen randomly selected, prospective blood donors were studied. Single fingerstick blood samples were obtained to determine the donors'' haemoglobin levels by HemoCue, while venous blood samples were drawn for measurement of the haemoglobin level by both HemoCue and an automated haematology analyser as the reference method. The sensitivity, specificity, predictive values and correlation between the reference method and HemoCue were assessed. Cases with a haemoglobin concentration in the range of 12.5–17.9 g/dL were accepted for blood donation.

Results

Analysis of paired results showed that haemoglobin levels measured by HemoCue were higher than those measured by the reference method. There was a significant correlation between the reference method and HemoCue for haemoglobin levels less than 12.5 g/dL. The correlation was less strong for increasing haemoglobin levels. Linear correlation was poor for haemoglobin levels over 18 g/dL. Thirteen percent of donors, who had haemoglobin levels close to the upper limit, were unnecessarily rejected.

Discussion

HemoCue is suitable for screening for anaemia in blood donors. Most donors at Yazd are males and a significant percentage of them have haemoglobin values close to the upper limit for acceptance as a blood donor; since these subjects could be unnecessarily rejected on the basis of HemoCue results and testing with this method is expensive, it is recommended that qualitative methods are used for primary screening and accurate quantitative methods used in clinically suspicious cases or when qualitative methods fail.     

Comparison of two methods of measurement of whole blood glucose in the neonatal period

The purpose of this study was to compare the performance and accuracy of the HemoCue B-Glucose photometer system and reagent strip tests used in conjunction with reflectance photometry against a reference plasma glucose method. One hundred consecutive babies admitted to the neonatal unit over a 6-month period were enrolled in the study. Each baby had a heelprick capillary glucose measured by HemoCue and reagent strip tests. At the same time venous plasma glucose and haematocrit were measured. The mean difference between the reagent strip test and plasma glucose was significantly less than the corresponding value for the HemoCue (0. 015 ± 1. 41 vs 0. 837 ± 1. 565 mmol 1^-1, mean ± SD); however, the agreement limits between both methods and plasma glucose were wide. No significant effect of haematocrit was detected on either method. The HemoCue photometer does not offer any advantage over the widely used reagent strip tests in the neonatal period. However, the limits of agreement of both methods compared with plasma glucose are too wide to be clinically acceptable in the neonatal period.     

Comparison of the Analytic Performance Between the B-HB and HB-201+ HemoCue® Hemoglobinometers for Venous and Capillary Blood Under Field Work Conditions

This study aimed at comparing the performance of the Hb-201+ and B-Hb HemoCues under field work conditions with 62 indigenous schoolchildren. The microcuvettes were filled with capillary and venous blood. Mean Hb using the Hb-201+ and B-Hb was 13.0 and 13.2 g/dL for venous blood, and 13.7 and 13.5 g/dL for capillary blood, respectively. The intraclass correlation coefficient was high (0.95, p<0.01) between the instruments for venous blood, but it was lower (0.85 p<0.01) for capillary blood. These results show differences in capillary Hb measurements; attempting combined use of these devices using capillary blood could affect the results of a study or survey.     

Improved strategy for screening prospective blood donors for anaemia

SUMMARY. Women (568) and men (531) attending blood donation sessions in Wessex in September, 1992, were assessed for anaemia by the standard CuSO₄ method on finger-prick (FP) blood samples. The haemoglobin (Hb) concentration on FP samples and on venous blood was also checked using the HemoCue. Different FP samples from the same donors revealed a wide variation on HemoCue. We recommend retaining the CuSO₄ method on FP samples as the initial screen, and follow-up of apparent failures by determining the Hb concentration on venous sampling with the HemoCue. As 54% of females were found on venous samples to be below the current recommended threshold (125 g/L) for Hb concentration, we also recommend lowering the threshold to 115 g/L for women, and to 130 g/L for men. We further recommend a close re-examination of normal haematology values for adults.     

HemoCue photometer: a better alternative of hemoglobin estimation in blood donors?

Purpose of study

To find out the prevalence of anemia in potential blood donors and to compare the direct cynmethemoglobin and HemoCue methods for assessing hemoglobin concentration.

Material and methods

The study group included 540 potential blood donors; who were tested for their hemoglobin concentration in capillary blood samples by direct cynmethemoglobin and HemoCue methods.

Results

Average age of the potential donors was 39.2 year, with 505 males and 35 females. Mean hemoglobin concentration using the HemoCue was 13.2 ± 2.4 g/dl and 12.8 ± 2.3 g/dl with the direct cynmethemoglobin method (Table 1). The prevalence of anemia was slightly higher when using the direct cynmethemoglobin method (14.1%) as compared to HemoCue method (13.6%). The sensitivity and specificity for the HemoCue assessment was 94.1% and 95.2% respectively as compared to 90.1% and 94.2% respectively for the direct cynmethemoglobin method.

Conclusion

Photometric hemoglobin determination (HemoCue) combines the convenience of onsite testing with sufficient accuracy and rapidity. We feel this is a better method for evaluating potential blood donors.     

Utility of point‐of‐care haemoglobin measurement in the HemoCue‐B haemoglobin for the initial diagnosis of anaemia

Measurement of haemoglobin (Hb) concentration provides a reliable indication of the presence and severity of anaemia. However, other laboratory parameters are usually requested as well, leading to an increase in socio‐sanitary costs. Accordingly, this study was undertaken to ascertain the reliability of point‐of‐care Hb determination with the portable photometer HemoCue‐B haemoglobin (HBH) and to evaluate its utility for the initial diagnosis of anaemia. Hb was measured (×3) in 20 venous blood samples diluted with saline (v/v; 1 : 0, 2 : 1, 1 : 1, 2 : 1 and 3 : 1) to obtain a wide range of Hb and in venous and capillary blood samples from 247 primary health care patients. All HBH results were compared with those yielded by the reference cell counter Pentra 120 Retic (ABX). In diluted samples, Hb values obtained with either method were not significantly different (ABX–HBH, ?0.01 ± 0.32 g/dl; 95% CI, ?0.04 to 0.028 g/dl) and showed an excellent Pearson's coefficient of correlation (r = 0.992; P < 0.01). HBH provides accurate values if at least 4 μl of blood is loaded into the cuvette. There were no significant differences between Hb measured in venous (v) and capillary (c) blood samples in primary care patients. Eighteen anaemic patients were detected by ABX measurements (7.3%; 15 female/3 male), 18 by HBHv (specificity, 100%; sensitivity, 100%) and 25 by HBHc (eight false positives; one false negative; specificity, 94.4%; sensitivity, 96.5%). Compared with ABX, HBH provides accurate and precise measurements for a wide range of Hb and its use in primary health care seems to be a good method for the initial diagnosis of anaemia.     

Accuracy Evaluation of Blood Glucose Monitoring Systems in Children on Overnight Closed-Loop Control

This pilot study evaluated the difference in accuracy between the Bayer Contour® Next (CN) and HemoCue® (HC) glucose monitoring systems in children with type 1 diabetes participating in overnight closed-loop studies. Subjects aged 10-18 years old were admitted to a clinical research center and glucose values were obtained every 30 minutes overnight. Glucose values were measured using whole blood samples for CN and HC readings and results were compared to Yellow Springs Instrument (YSI) reference values obtained with plasma from the same sample. System accuracy was compared using mean absolute relative difference (MARD) and International Organization for Standardization (ISO) accuracy standards. A total of 28 subjects were enrolled in the study. Glucose measurements were evaluated at 457 time points. CN performed better than HC with an average MARD of 3.13% compared to 10.73% for HC (P < .001). With a limited sample size, CN met ISO criteria (2003 and 2013) at all glucose ranges while HC did not. CN performed very well, and would make an excellent meter for future closed-loop studies outside of a research center.